HR: 08:45h
AN: S11D-04    [Abstracts]
TI: Correlation of Seismic Noise From an OBS Aarray off Costa Rica
AU: * Dorman, L M
EM: ldorman@ucsd.edu
AF: LeRoy M. Dorman Scripps Inst of Oceanography, UCSD, 9500 Gilman Drive, MC0220, La Jolla, CA 92093-0220,
AB: The CRSEIZE experiment of 1999-2000 (DeShon and others, 2006), an array of 14 "ONR" OBSs were deployed in an array across the forearc of the subduction zone west of Costa Rica. The station spacing was about 15 km and the array was about 35km by 60km. Half the sensors were PMD broadband electrochemical seismometers and half were 1-Hz inertial sensors. Since the length of this deployment was about six months, the dataset offers an opportunity to exploit recently-developed techniques exploiting microseismic noise as a tool for structural analysis. See Shapiro and others, 2005, as a starting point. For this technique to work, there must be coherent observations of propagating seismic waves between pairs of stations. Practically, this means that the there must be some frequency ranges where propagating seismic signals are not contaminated by local non-propagating noise. Twelve-hour samples of field data, which were sampled at 64 Hz, were desampled to 1 Hz for this reconnaissance analysis. Data from the vertical sensor were whitened and cross-correlated, basically following Gerstoft and others, 2006. The resulting correlograms were noisier than the best data which is being shown from land sensors but there are recognizable arrivals, mostly at periods of around 7 and 3.3 seconds. No well-dispersed waveforms have been seen yet. At the present time, there are too few arrivals to identify unequivocally.
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Seismology [S]
MN: 2007 Fall Meeting